Background

Our design was inspired by our own frustrating experiences dealing with cold hands in the winter. We noticed that doing even basic outdoor activities was difficult because of the size and lack of dexterity imposed by sufficiently warm gloves. Thus, we decided to try and spread heat from the user’s arms down to their wrists. While this wouldn’t directly warm the user’s fingers, it would transmit heat out to the user’s wrists. Then a similar strategy could be used to spread heat out from the user’s palm

Materials Testing

In order to determine what material and form would be most
effective for our target thermo-conduction, we tested a variety of materials,
including a copper-infused polyester, copper wire, basic conductive fabric, and
tin/copper metal soldering wire of various thicknesses. To test the conductive
power of these materials, we used a hotplate to introduce heat to one end of
the material and then tracked the movement of that heat through the material
using a FLIR ONE Personal Thermal Imager.

Findings

A summary of our findings is as follows: The copper-infused
polyester had such a low overall copper content that thermo-conduction was
essentially non-existent (which is interesting, because gloves of these
material are specifically marketed as heat conducting from a hand warmer pouch
in the palm out to the fingers). The copper wire was too thin for substantial
heat conduction, but the tin/copper metal soldering wire (much thicker, approx.
1cm thick) demonstrated significant thermo-conductive capabilities. For our
final and most comprehensive experiment, we cut an arm’s length (from armpit to
end of wrist) strip of this wire, then created an approximate 65 degree
difference between the wire temperature and the hotplate, approximately
mirroring the difference between a body at 95 degrees and a freezing external
temperature of 30 degrees. We insulated this wire along its full length (except
for the end tips), and found that after about 5 minutes, the measured
temperature of the end of the wire was 82 degrees.

Key Take-Aways

Though we are skeptical about how significant such a 2
degree difference at the base of the hand would feel to the extremities of an
athlete outside in the freezing cold, our experiments did illuminate some key
design elements to consider:

1. Insulating the conductive medium is key; there
was noticeably better thermos-conduction for all materials tested when the
material was imbedded in Styrofoam to keep the heat from the hotplate from
escaping radially into the air

2. Metal-infused fabric materials such as polyester
would have to be infused at a very high concentration in order to yield
significant conduction

3. Thermal conduction rarely extended the full
length of the material tested; though we pursued only dry materials to test for
this Challenge, the idea of using fluid as a thermo-conductive medium is
appealing because basic motion of the athlete would circulate the fluid through
the garment and hopefully improve heat dissipation from the armpits to the
extremities.